Where is the blow off valve located on the Audi A4 1.9TDi

As a general rule if this occurs then the valve guide seals are worn. (Located in the "head") of the engine block. Usually requires a "head" job by a mechanic.
You may also have excessive wear on the piston rings
and bores. This can be checked by having a compression check on all cylinders to
see if it is within specifications.
One last thought. If the PCV valve is failing this may occur as well. (Positive crankcase
ventilation). An inexpensive part, They can usually be checked by removing them and
blowing into them but I generally just replace them (generally less than 10 dollars).

Hi,
This will help you out.

Where is intake manifold valve location on Passat 98 not turbo and i need photo for manifold valve n156

The thermostat is located in front of the engine, between V cylinder banks, for Audi A8 V8 4.2 Quattro Automatic. See pictures below:




Remove the thermostat housing (2 bolts) and the old thermostat. Note the orientation of the old thermostat (vent valve facing UP). Clean both thermostat housing and block surfaces and remove all traces of old gasket material. Install the new thermostat vent valve facing UP.

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This is a known fault with new shape A6's. The heater control valve (located within the bulkhead within the engine compartment) sticks thus causing hot air to vent out of one side whilst the other side stays cold. Audi have issued a Technical Service Bulletin (TSB) regarding this problem and if your car is within its warranty period they will repair free of charge - if not you are looking at a cost of £250 for a new valve. In true Audi honoured tradition they don't admit to the problem being a design fault despite new valves being modified to prevent it happening in future!! A temporary solution is to turn the climate control dial to max (Hi) then to min (Lo) which should free the valve off until it sticks again. Details and a picture of the valve can be found on the audiworld forum

Thermostat is located in front of the engine between V cylinder banks, for Audi 4.2 V8.




Remove the thermostat housing (2 bolts) and the old thermostat. Note the orientation of the old thermostat (vent valve facing UP). Clean both thermostat housing and block surfaces and remove all traces of old gasket material. Install the new thermostat vent valve facing UP.
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heater core clogged or heater valve

SYNAPSE ENGINEERING - Synchronic Blow Off Valve SB001 Synapse Engineering Part # SB001A

Prices range vary ,ebay etc

Normal, indicates oil cleaning engine. Change oil every 3000 miles. Car may be running a little rich, have oxygen sensors checked, located on manifold underneath car. Also check egr valve for leak.

they told me it was the a/c server some kind of valve that switches it to cold or hott mine just has cold air coming out check they its under ur dash so look it up on line and look for it , its about 80 to 100 dollars.......